Hydrophobic aggregation and collective absorption of dioxin into lipid membranes: insights from atomistic simulations

Dioxins are a highly toxic class of chlorinated aromatic chemicals. They have been extensively studied, but several molecular-level details of their action are still missing. Here we present molecular dynamics simulations of their absorption and diffusion through cell membranes. We show that, due to their hydrophobic character, dioxins can quickly penetrate into a lipid membrane, both as single molecules and as aggregates. We find clear evidence for their ability to accumulate in cell membranes. Our free energy calculations indicate that subsequent transport into the cell is unlikely to be a simple diffusive process

C-reactive protein monitoring in children with acute asthma

Cilj: Ispitati može li se određivanje koncentracije hsCRP (high sensitivity C-reactive protein) primijeniti kao biomarker u praćenju uspješnosti terapije akutne egzacerbacije astme u djece. Ispitanici i metode: U ispitivanje je uključeno 28-ero djece kontrolne skupine i 27-ero djece hospitalizirane zbog liječenja akutnog napadaja astme. Liječenje akutne egzacerbacije provedeno je kontinuiranom inhalacijom 2-agonista brzog djelovanja te primjenom inghalacijskih kortikosteroida. Za određivanje hsCRP uzorkovani su serumi bolesnika prije terapije i tri dana nakon terapije. Koncentracija hsCRP određena je imunoturbidimetrijskom metodom na lateks česticama na biokemijskom analizatoru AU400. Rezultati: Koncentracija hsCRP bila je statistički značajno veća u djece s astmom (prije terapije: 3,00 ± 1,92 mg/l; tri dana nakon terapije: 0,80 ± 0,61 mg/l) nego u djece kontrolne skupine (0,36 ± 0,21 mg/l). Zaključak: Rezultati ovog istraživanja ukazuju na to da bi hsCRP mogao biti nespecifičan biomarker za praćenje upale u djece s akutnom egzacerbacijom astme. Međutim, potrebna su nova istraživanja koja bi utvrdila korelaciju između specifičnih i nespecifičnih biomarkera upale u astmi.Aim: To assess whether the determination of high sensitive C-reactive protein (hsCRP) could bi used as biomarker of successful drug administration in children with asthma exacerbation. Subjects and methods: The study included 28 control children and 27 pediatric asthmatics who were hospitalized for treatment of asthma exacerbation. All patients were treated with continuous inhalations of short acting 2-agonists and inhaled corticosteroids administration. A pair of routine serum samples (one taken before and one three days after drug administration) were taken for hsCRP determination. The concentration of hsCRP was determined by the immunoturbidimetric method on latex particles on an Olympus AU400 biochemistry analyzer. Results: The concentration of hsCRP was statistically significantly higher in children with asthma (before drug administration: 3.00 ± 1.92 mg/L; three days after drug administration: 0.80 ± 0.61 mg/L) than in healthy children (0.36 ± 0.21 mg/L). Conclusion: Study results suggest that hsCRP could have the potential as a nonspecific biomarker for monitoring inflammation in children with asthma exacerbation. Further research is are needed to find the correlation between specific and nonspecific biomarkers of inflammation in asthma

Early Stages of Homopolymer Collapse

Interest in the protein folding problem has motivated a wide range of theoretical and experimental studies of the kinetics of the collapse of flexible homopolymers. In this Paper a phenomenological model is proposed for the kinetics of the early stages of homopolymer collapse following a quench from temperatures above to below the theta temperature. In the first stage, nascent droplets of the dense phase are formed, with little effect on the configurations of the bridges that join them. The droplets then grow by accreting monomers from the bridges, thus causing the bridges to stretch. During these two stages the overall dimensions of the chain decrease only weakly. Further growth of the droplets is accomplished by the shortening of the bridges, which causes the shrinking of the overall dimensions of the chain. The characteristic times of the three stages respectively scale as the zeroth, 1/5 and 6/5 power of the the degree of polymerization of the chain.Comment: 11 pages, 3 figure

Techno-economic evaluation of buffered accelerated weathering of limestone as a CO2 capture and storage option

Carbon dioxide storage technologies are needed not only to store the carbon captured in the emissions of hard-to-abate sectors but also for some carbon dioxide removal technologies requiring a final and permanent storage of CO2. The pace and scale of geological CO2 storage deployment have fallen short of expectations, and there is a growing interest in ocean-based CO2 storage options. As complementary to geological storage, buffered accelerated weathering of limestone (BAWL) has been proposed to produce a buffered ionic solution at seawater pH, derived from the reaction in seawater between a CO2 stream and a micron-sized powder of calcium carbonate (CaCO3), within a long tubular reactor. The addition of calcium hydroxide to buffer the unreacted CO2 before the discharge in seawater is also envisaged. BAWL avoids the risks of CO2 degassing back into the atmosphere and does not induce seawater acidification. This work presents a mass and energy balance and preliminary cost analysis of the technology for different configurations of discharge depth (100, 500, 3,000 m), pipeline length (10, 25, 100 km) and diameter of CaCO3 particles (1, 2, 10 mu m) fed in the tubular reactor. The total energy consumption to capture and store 1 t of CO2 generated by a steam-methane reforming (SMR) process ranges from 1.3 to 2.2 MWh. The CO2 released from the CaCO3 calcination to produce the buffering solution leads to a total CO2 storage requirement 43-85% higher than the CO2 derived by SMR. The total cost to capture and store 1 t of CO2 from SMR is estimated in the range 142-189 euro

Electron transport in crystalline PCBM-like fullerene derivatives: a comparative computational study

We present an extensive study of electron transport (ET) in several crystal forms of phenyl-C61-butyric acid methyl ester (PCBM) and 1-thienyl-C61-butyric acid methyl ester (ThCBM) fullerene derivatives. Our calculations are based on a localized representation of the electronic states. Orbital couplings, site energies and reorganization energies have been calculated using various density functional and semi-empirical techniques and used within the Landau–Zener, Marcus and Marcus–Levich–Jortner expressions to evaluate electron transfer rates. Electron mobilities have been then estimated by kinetic Monte Carlo (KMC) simulations. The adiabaticity of electron transfer directions within the different crystal structures has also been verified using the Landau–Zener expression. Finally, the role of low energy virtual orbitals of the fullerene molecules has been investigated using charge transport networks of increasing complexities. Our results show that these molecules may form one-, two- or three-dimensional percolation networks and that their higher energy orbitals often participate in ET. The highest mobility values were obtained for the crystal structure of ThCBM and are comparable to experimental values

An integral equation approach to effective interactions between polymers in solution

We use the thread model for linear chains of interacting monomers, and the ``polymer reference interaction site model'' (PRISM) formalism to determine the monomer-monomer pair correlation function $h_{mm}(r)$ for dilute and semi-dilute polymer solutions, over a range of temperatures from very high (where the chains behave as self-avoiding walks) to below the $\theta$ temperature, where phase separation sets in. An inversion procedure, based on the HNC integral equation, is used to extract the effective pair potential between ``average'' monomers on different chains. An accurate relation between $h_{mm}(r)$, $h_{cc}(r)$ [the pair correlation function between the polymer centers of mass (c.m.)], and the intramolecular form factors is then used to determine $h_{cc}(r)$, and subsequently extract the effective c.m.-c.m. pair potential $v_{cc}(r)$ by a similar inversion procedure. $v_{cc}(r)$ depends on temperature and polymer concentration, and the predicted variations are in reasonable agreement with recent simulation data, except at very high temperatures, and below the $\theta$ temperature.Comment: 13 pages, 13 figures, revtex ; revised versio

ENERGY EFFICIENCY AND USE OF RENEWABLE ENERGY SOURCES IN BUILDINGS CONSTRUCTION- PERSPECTIVE OF SUSTAINABLE DEVELOPMENT

In this paper are presented the overall energy needs of the buildings and measures to improve energy efficiency in buildings. It is shown the importance of sustainable construction as one of the important segments of environmental protection and sustainable development. It is also pointed out the importance of use of renewable energy sources in the construction of energy efficient buildings